Does your gerbil have a swollen abdomen? Does he suffer from frequent diarrhea? Has he recently lost weight? Your gerbil may be suffering from intestinal parasites or worms.

Internal Parasites
Several types of tapeworms and pinworms can infest gerbils.

Tapeworms - If you see small square or cucumber seed-like white segments in your gerbil's feces or around his anus, he likely has tapeworms. Sometimes, you may see these segments moving.

Pinworms - If your gerbil has irritation in the anal area, he may have pinworms. You may also see an adult worm in your gerbil's feces.

If you suspect your gerbil has intestinal parasites, contact your veterinarian to set up an exam. He or she will examine your gerbil's feces under a microscope - looking specifically for worm eggs, which indicate a parasitic presence in your pet. Be aware, however, that other conditions can cause a swollen belly, diarrhea, and/or weight loss.

External parasites
Gerbils may also have external parasites such as fleas and mites, and to a lesser extent, ticks. You will be able to see fleas and ticks, but mites are difficult to see with the naked eye and microscopic examination may be necessary. If your gerbil shows signs of dry skin, dandruff, hair loss, or relentless scratching, consult your veterinarian. Use only those pesticides recommended by your veterinarian, and remember, you may also need to treat your gerbil's cage and possibly your house.